1. Field of the Invention
The present invention relates to a display device. The invention particularly relates to a liquid crystal display device that can be formed as a so-called narrow frame type in which a display region is made larger relative to a predetermined outer shape.
2. Description of the Related Art
A liquid crystal display device has a TFT substrate and a counter substrate opposed to the TFT substrate. The TFT substrate includes pixels arranged in a matrix, each pixel having a pixel electrode and a thin film transistor (TFT). The counter substrate includes a color filter formed at a position corresponding to a position at which the pixel electrode is located above the TFT substrate. Liquid crystals are put between the TFT substrate and the counter substrate. Images are formed by controlling the light transmittance of liquid crystal molecules for every pixel.
Since liquid crystal display devices are flat in shape and light in weight, their uses have been extended in various fields. Small-sized liquid crystal display devices have been used generally, for example, in mobile phones or DSC (Digital Still Camera), etc. For the small-sized liquid crystal display devices, there is a strong demand to enlarge a display region while keeping the outer shape of the device small. Then, the width between the end of the display region and the end of the liquid crystal display device becomes narrow and so it is necessary to provide a so-called narrow frame.
A seal member for bonding the TFT substrate and the counter substrate is applied to a narrow frame region. On the other hand, an alignment film for initial alignment of liquid crystals is formed in the display region of the liquid crystal display device. Since it is necessary that the alignment film cover the display region reliably, the area to coat the alignment film has to be larger by a predetermined width than that of the display region. On the other hand, when the alignment film is present between the seal member and the TFT substrate or between the seal member and the counter substrate, the reliability of bonding by the seal member will deteriorate. Accordingly, the alignment film should not overlap with the seal member. Even if the alignment film and the seal member overlap each other, it is necessary that the overlapping region extend not over the entire surface thereof but partially.
The alignment film has been formed by flexographic printing. Since, in the flexographic printing, the viscosity of the alignment film before baking can be made higher, the outer shape of the alignment film can be controlled accurately. On the other hand, the market recently requires various types of sizes for the liquid crystal display devices. When the flexographic printing is used, the printing plates have to be prepared for every size, resulting in problems in the manufacturing cost of the printing plates and the number of steps in the line of exchange the printing plates.
Manufacturing the alignment film by ink jet printing may cope with manufacture of liquid crystal display devices of various types and various sizes. However, when the alignment film is to be formed by ink jet printing, it is necessary to lower the viscosity of the alignment film. However, if the viscosity of the alignment film is low, the alignment film flows out to the outside after coating of the alignment film, thus making it difficult to accurately control the outer shape of the alignment film.
JP-A-2008-145461 describes that unevenness is formed at the periphery of an under layer film forming the alignment film to use the unevenness as a stopper when the alignment film flows to the outside after coating.